ROP Advice

Been browsing the forum for the past few months but this is my first post.

I have been working at collecting parts for the rop mod as a fun project for the beginner flashlight enthusiast. However I am not thrilled with the results and am wondering what I could do to improve my setup.

Here is what I am using:

2d mag
6 aa Eneloops
2 Titanium Innovations 3aa > 1d series adapters. http://www.batteryjunction.com/titanium-3aa1d-ser-adapter.html
3854 Pelican Hi/lo bulbs

I suspect the adapters are the problem. I see that older posts have always recommended the 6aa to 1d adapters but I can't seems to find them anymore.

When I hold the two adapters together I measure 7.92v. With the light switched on I measure 1.8 amps with the Low bulb and 3.6amps with the high. I have no way of measuring lumens or output. I am happy with the low bulb though I wish it were a little whiter and not such a pale yellow. But the high bulb seems hardly any brighter than the low.

Would different batteries help? Could anyone point me to a better adapter if that is the problem? Should I work at lowering resistance in tail cap/switch? Apologies if this is all very obvious but I have done quite a bit of searching in the forums and can't find anything very recent or that addresses this issue. I understand it's an old subject but it interests me and I am learning a bit and enjoying it.

Thanks.

PreservedKillick said:

Been browsing the forum for the past few months but this is my first post.

I have been working at collecting parts for the rop mod as a fun project for the beginner flashlight enthusiast. However I am not thrilled with the results and am wondering what I could do to improve my setup.

Here is what I am using:

2d mag
6 aa Eneloops
2 Titanium Innovations 3aa > 1d series adapters. http://www.batteryjunction.com/titanium-3aa1d-ser-adapter.html
3854 Pelican Hi/lo bulbs

I suspect the adapters are the problem. I see that older posts have always recommended the 6aa to 1d adapters but I can't seems to find them anymore.

When I hold the two adapters together I measure 7.92v. With the light switched on I measure 1.8 amps with the Low bulb and 3.6amps with the high. I have no way of measuring lumens or output. I am happy with the low bulb though I wish it were a little whiter and not such a pale yellow. But the high bulb seems hardly any brighter than the low.

Would different batteries help? Could anyone point me to a better adapter if that is the problem? Should I work at lowering resistance in tail cap/switch? Apologies if this is all very obvious but I have done quite a bit of searching in the forums and can't find anything very recent or that addresses this issue. I understand it's an old subject but it interests me and I am learning a bit and enjoying it.

Thanks.

Click to expand...

You need decent adapters. If you can find some in market place, expect to pay around $30 or more.
For unbored mag you want 6 x AA series adapter which will need a 2D mag. You'll have around 7.2V, 2000mAh.

Cheaper and simpler is 2 x 18650s. All you need is a sleeve. Shorten tail spring slightly.
3400mAh cells available but the LION cells have a steeper discharge curve, so compared to Eneloops I would think 2800mAh - 3000mAh would be a fairer comparison to Eneloops. The LIONs will give much longer run time but a longer dimming period.

For good ROP H performance you need to do some resistance mods in a Mag, tailcap spring and the PR bulb holder can be modded for lower resistance and you'll get closer to 4.4Amps.

Or just be happy with that light as ROP low. The lower the current, the less significant the high resistance losses of a stock Mag.
Do some resistance mods and you might get to 2 Amps with ROP L.

Most likely, the adaptors are to blame. Few adaptors are truly designed around high current usage. So chances are, you are losing quite a bit through the adaptors. If youncan get better adaptors, it might also help to get better batteries. Eneloops can typically handle 4A. But a higher current battery such as Elites can maintain a significantly higher voltage during discharge.

Li-Ion is also a choice. But, as the other guy said, due to the downsloping nature of the discharge curve Li-Ion batteries, you will tend to get a dimming output similar to an incandescent flashlight powered by alkaline batteries. You can minimize this somewhat by going with 26650s instead of 18650s, as they have a somewhat flatter discharge curve (and are no worse of a fit than 18650s in a 2D Mag). You can even get 32600s at Fast Tech, which will fit like regular D cells (ie no need to use sleeves, and no tailspring mods). And, with 5000mAH of capacity, runtime will be better than even 26650s (over an hour on the Hi bulb). But with the exception of LiFePO4 (which doesn't produce sufficient voltage with only two), no Li-Ion battery has anything approaching the discharge curve of NiMH.

Lastly, if you don't mind a large light, you can go with a 6D and fill it with Tenergy Premiums or Centuras. Yes, the light is big. But there are NO current problems here. Plus, you will get 2-2.5hr of BRIGHT runtime with this setup on the Hi bulb!

Thanks for explaining about the different discharge curves, that was new to me. Li-ion definitely seems the simplest. I bought the AA adapters originally just to brighten up my old 2D MAG a bit. When I saw others have had success with 6 Eneloops and a Pelican bulb I thought I'd give it a try, so I began collecting parts for the ROP.

I like the idea of using Li-Ions but, as I said, I'm pretty much a beginner at this flashlight thing. (Up until a few months ago I didn't even know what a Li-Ion battery was. In fact it was an inquiry as to whether I should use AA lithium primaries in my new mini MAG LED that led me to this humble forum.) So that will have to be a future project. Using a 6D MAG sounds like simplicity itself.

Thanks again for the advice. Now that I have finally taken the time to create an account I should be around more.